Circuit interrupter



Dec. 11, 1934. A C. SCHWAGER 1,984,035

G IRGUI'I INTERRUPTER Filed May 8, 1934 Sheets-Sheet l Dec. ll, 1934. A.c. scHwAGi-:R 1,984,035

CIRCUIT INTERRUPTER Filed May 8, 1934 2 Sheets-Sheet 2 Patented Dec. 1i,1934 UNITED STATES CIRCUIT INTEBRUPTEB `August C. Schwager, Sanlanclsco,

Calif., as-

signor to Pacific Electric Manufacturing Corporation, California SanFrancisco, Calif., a

corporation of Application May 8, 1934, Serial No. 724,505

5 Claims.

The present invention relates to an electric circuit interrupter, andmore particularly to a circuit interrupter of the type wherein the arcbetween the separating contacts of the interrupter is confined within anarcing chamber, to decompose a gas producing medium, and subjected tothe deionizing action of a blast of gas to extinguish the arc.

An object of the invention is to provide a new and improved circuitinterrupter in which the arc between its separating contacts will besubjected to a blast of gas substantially immediately upon contactseparation.

Another object of the invention is to provide an improved arcextinguishing chamber for an alternating current circuit interrupterwhich will subject the arc to a deionizing high velocity blast of gas atthe first current zero after contact separation.

Another object of the invention is to provide an arcing chamber for analternating current circuit interrupter which will subject the arcbetween the separating contacts to an elongating and deionizing blast ofgas within a half cycle of current fiow.

Another object of the invention is to provide, in connection with anarcing chamber for a circuit interrupter of the gas-blast type, a meanswhich will facilitate an elongation of the arc, under the influence of ablast of gas, independently of the contact separation.

Another object of the invention is to provide, in connection with thearcing chamber of a circuit interrupter of the gas-blast type, a meanswhich, inv cooperation with a blast of gas from the chamber, willproduce an elongation of the arc in a substantially straight lineindependently of the contact separation.

Other objects and advantages of the invention will be in part point-edout and in part evident to those skilled in this art as the descriptionthereof proceeds.

The objects of this invention are obtained by interrupting theelectrical circuit in an arcing chamber in close proximity with anysubstance which will generate a gas upon the application of heat, suchas is the case when an electrical arc is drawn between a pair ofseparating contacts under an insulating oil, and confining the gasgenerated in this way so that it cannot escape from the chamber exceptby subjecting the arc between the separating contacts to an elongatingand deionizing action of a high velocity blast of inert gas.

,When the contacts of a circuit interrupter are (Cl. 20D-150) separatedunder the surface of oil or other fluid,

as is the case in an ordinary oil circuit breaker, the uid will bedecomposed and form a gas bubble around the arc. If the arc ismaintained, the high temperature created thereby will contin- 5 uouslygenerate more gas at the inner surface of the bubble and as a result thebubble will rapidly increase in size. This growth of the gas bubble inthe oil circuit breaker is a factor which works against the extinctionof the arc, because it permits the oil boundary to move out from the arcand thus reduces the rate of decomposition of the oil.

In the earliest application of this principle the switch contacts wereseparated within an exl5 plosion chamber disposed below the surface ofan insulating fluid and the gas generated by the arc was confined withinthe explosion chamber until the moving contact was withdrawn through asmall throat in one end of the chamber. When the moving contact of thisswitch was thus withdrawn from the explosion chamber the confined gasescaped through the throat of the chamber and subjected the arc, at thispoint, to the deionizing effect of a longitudinal blast of the confinedgas. A disadvantage of this arrangement is that the arc must be drawnthrough the throat in the explosion chamber and consequently the arccannot be extinguished until after several cycles of current flow'havetaken place. If the arc is con- 30 fined within the explosion chamberfor a considerable length of time, the pressure generated therein willbecome very high. This pressure can be reduced by providing a throatopening of a larger diameter than the movable contact which passestherethrough and while such a construction is effective at high currentvalues, it reduces the effectiveness of the switch at low currentvalues. In the case of low current values the volume of gas generated iscomparatively e I small and, therefore, if part of the gas is expelledfrom the chamber before the movable contact leaves the throat, the gasremaining in the explosion chamber will escape at such a low 'velocitythat the arc will not be immediately interrupted, but will persist untilthe contact separation is sufficient to break the arc.

From the above it will be seen that when the switch is equipped with anexplosion chamber of the type referred to, the circuit interruptioncannot take place until after the movable contact has left the throat ofthe explosion chamber, as it is not until this moment that the arcextinguishing action of the vgas blast can function.

The efficiency oi.' the rupturing performance of. 55

is not practical.

a gas blast circuit interrupter is directly proportional to theeffectiveness of the means provided for preventing the escape of gasgenerated in the vicinity of the arc without passing through the arcstream. Therefore, it will be seen that tosbe most effective the circuitinterrupter must be capable of drawing and maintaining an arccontinually in contact with fresh oil to produce a high rate ofdecomposition of the oil, and that the shape and size of the arcingchamber must be such as to force all of the generated gas or otherproducts of decomposition to pass through the arc. If these conditionsare fulfilled, the rate of recovery of dielectric strength in the arcstream after a current zero will be adequate to cope successfully withthe rate atwhich recovery voltage will build up across the arc terminalsunder any circuit conditions to be found in practical service.

-It is known that an alternating current a'rc can be extinguished at thefirst current zero which occurs after the contacts of the interrupterhave separated. However, since the current to be interrupted will have azero value every half cycle, during the continuance of the arc, it willbe seen that a number of half cycles of current flow will occur withinan arcing chamber of the above type before the moving contact can bewithdrawn from the explosion chamber and subjected, at a zero currentvalue, to the deionizing action of a blast of gas escaping from theexplosion chamber. This condition can be remedied by causing the movingcontact to travel at a high rate of speed, but an increase in theoperating speed of the contact requires additional operating force andresults in unduly increased mechanical stresses and Therefore, it may besaid that a further object of the present invention is to provide inacircuit interruptenof the gas-blast type, a means which will cause thearc to travel along va conducting surface in a direction opposite to thedirection of travel of the moving contact, whereby the arc will be morerapidly elon-v gated without increasing the speed of travel of themoving contact.

For a better understanding of this invention reference should be had tothe accompanying drawings wherein there are shown, by way ofillustration and not of limitation, several embodiments thereof.

In the drawings, wherein like numerals refer to v like parts throughoutthe several views;

Figure 1 is a vertical sectional view taken centrally through anexplosion chamber, for a conventional drop bar type of oil circuitbreaker, constructed in accordance with this invention,

Figure 2 is a sectional view taken along line II--II of Figure l,looking in the direction of the arrows,

Figure 3 is a perspective view of the explosion chamber lining membershown in Figure 1,

Figures 4 and 5 are fragmentary sectional views showing modifications ofthe structure illustrated in Figure 1,

Figure 6 is a sectional view of an explosion chamber, for a so-calledrotary type of circuit interrupter, embodying the present invention,

Figure I is a diagrammatic plan view showing the manner of arranging theexplosion chambers illustrated in Figure 6 when used with a multiplebreak rotary type of circuit interrupter,

'Figure 8 is a perspective View of the arcing chamber lining memberillustrated in Figure 6,

Figure 9 shows a detail of one of the parts, and

Figure 10 is a fragmentary sectional view showing a modified form of thestructure illustrated in Figure 6. I

The embodiment of the invention chosen for illustration on Sheet 1 ofthe drawings is particularly adapted to a circuit interrupter of theso-called double break type in which the cooperating contacts aredisposed within an insulating uid containing receptacle and separate bya downward movement or dropping o f a cross bar, the ends of which carrya moving contact. In such an interrupter the contacts for each break andtheir associated elements are identical. Therefore, a showing of onlyone set of cooperatingcontacts and a single explosion chamberis thoughtsufficient.

In Figure '1 of the drawings, the numeral 10 designates a tank which isadapted to contain an insulating fluid 11. Projecting downwardly intothe tank 10 and terminating below the level of the insulating fluid 11,there is a supporting insulator 12. Extending through the insulator l2is a conductor 13 which is adapted to connect the interrupting contactswith an external circuit. vThe end of the conductor 13 carries a member14 which forms the upper end of an explosion chamber designatedgenerally by the numeral 15. In addition to the member 14, the explosionchamber 15 comprises a cylindrical member 16, having a strengthsuilcient to withstand high internal pressures, and a plug like member17 which is firmly secured in the lower end thereof. Mounted upon theinside of the member 14 and disposed at the upper end of the explosionchamber 15, there is a stationary contact 18 which will be described inmore detail hereinafter. Projecting through the plug like member 17, atthe bottom of the explosion chamber 15, and in line with the stationarycontact 18, is a vertically movable contact 19 which is carried by adrop bar 20, the movement of which is controlled by the switch operatingmechanism.

In order to secure an early interruption of the arc established by aseparation of the contacts 18 and 19 in interrupting a high tensioncircuit, it is important that the explosion chamber 15 be soproportioned that only suflicient fluid will be contained therein toproduce a violent explosion and consequently a high velocity flow of arcinterrupting gases. Therefore, the cylindrical member 16 is providedwith a lining member 21 which serves to take up considerable of thespace therein and thus reduce the size of the explosion chamber 15. Thislining member 21, as shown in Figure 2 of the drawings, forms what maybe termed a long narrow explosion chamber rather than a cylindrical one,such as would be provided if it were omitted. As shown in this latterfigure of the drawings, the stationary contact 18 is disposed at oneside of the explosion chamber 15 to provide room for a gas dischargeoutlet 22 through the member 14.

In Figure 3 of the drawings, the lower end of the lining member 21 .isillustrated as having a. key-way 23, by means of which it may be keyedagainst rotation within the cylindrical member 16 and at its upper end,in order to provide a clearance for the stationary contact 18 and thegas discharge outlet 22, it is cut away so as to form twosemi-cylindrical projections 24 which extend upwardly along each side ofthe stationary contact 18 and engage the under side of the member 14.Disposed beneath the lining member 21 are two transversely extendingdiscs 25 which are held apart by a. spacing ring 26. The discs 25 andthespacing ring 26 are also keyed within the cylindrical member 16. Thediscs 25 form an auxiliary compartment which will contain a reservesupply of the insulating iiuid 11 for the generation of additional arcextinguishing gas should the arc continue after the end of the movablecontact 19 has moved through this auxiliary compartment.

To properly direct the gas generated by an arc formed between thecontacts 18 and 19, so that it will travel at a high velocity in aneffective manner through and/or against the'arc, the gas dischargeoutlet 22 is located with its inner end disposed closely adjacent theinitial arc forming zone within the explosion chamber 15. This isaccomplished, in the embodiment of the invention illustrated in Figure 1of the drawings. by projecting an insulating tube 27 through the member14 so that its inner end extends into the explosion chamber 15 to apoint adjacent the lower end of the stationary contact 18. As a furtherassurance that the gases generated, within the explosion chamber 15 byan electric arc, will be effectively directed through the arc, thestationary contact 1B is provided with an arcing tip 28 which is soshaped that the arc between the separating contacts will be initiallydrawn at a point closely adjacent the inner end of the insulating tube27. At this point, it should be stated that the stationary contact 18comprises, in addition to the arcing tip 28, three contact making tips29 which are supported upon stili.' springs 30 extending outwardly froma supporting boss 31. To provide a low resistance path for the currentfrom the arcing tip 2B and the contact making tips 29, each tip has alaminated conductor 32 which extends therefrom to the supporting boss31.

With the above arrangement, it will be seen that upon the interruptionof a circuit an arc will be formed between the end of the movablecontact 19 and the arcing tip 28 and that as gas is generated thereby,within the explosion chamber 15, the arc will be blown into the gasstream, where it will be subjected to the deionizing action of the gas,as it exhausts from the explosion chamber 15 through the gas dischargeoutlet 22. Under these conditions the arc root upon the arcing tip 28will be carried toward the inner end of the insulating tube 27. As afurther and important aspect of the present invention there is provided,within the gas discharge outlet 22, an auxiliary current carryingconductor 33 which is connected to the stationary contact 18 at a pointexternally of the explosion chamber 15. This auxiliary current carryingconductor 33 extends through the insulating tube 27 so that its lowerend will be located closely adjacent the arcing tip 28 of the stationarycontact 18.

If the gas discharge outlet 22 is formed with an insulating tube 2'7, assuggested above, and the auxiliary conductor 33 is omitted, the upperroot of the arc established by a separation of the contacts will alwaysremain upon the arcing tip 28, but where the auxiliary conductor 33 isprovided the exhausting gas will carry the upper root of the arc over tothe auxiliary conductor 33 where it wi be blown into the gas dischargeoutlet 22 and finally extinguished.

It is well known that if the arc root is caused to travel along a coolmetal surface its temperature will be kept low and an interruptionthereof will be facilitated. Therefore, it will be seen that in thearrangement above described the arc interrupting means will becomeeffective to extinguish the arc substantially immediately upon contactseparation. It will also be seen that as the upper root of the-` arc isblown out along the auxiliary conductor 33 the length of the arc will beincreased independently of the travel of the moving contact 19.

It is also known that the velocity of a gas under pressure through acylindrical tube cannot exceed a velocity in excess of the soundvelocity of the particular gas under the conditions of temperature andpressure then existing. However, ii the gas discharge outlet 22 isshaped as a nozzle with a flaring end the velocity of the escaping gaswill be in excess of its sound velocity. Therefore, the gas dischargeoutlet 22 may, if desired, be constructed as illustrated in Figures 4and 5 of the drawings. In Figure 4 of the drawings, the gas dischargeoutlet 22 is formed by a funnel like member 34 which has a slightlyIiared portion 35 adjacent the arcing tip 28 and a longer Ilared portionwhich extends outwardly from a throat 36. Disposed within the funnellike member 34, there is an auxiliary conductor 37 which extends fron. apointadiacent the arcing tip 28 to a point external to the explosionchamber 15 where it is secured in electrically connected relation withthe base of the stationary contact 18 by means of a screw 38.

InFigure 5 of the drawings, there is shown a variation of the last abovedescribed arrangement wherein the gas discharge outlet 22 is provided byforming a ared outlet opening in the member 14, the lower end of theopening being carried down to a point adjacent the arcing tip 28 bycasting a tubular extension 39 upon the under side of the member 14.

Reference is now made to Sheet 2 of the drawings where, in Figure 6,there is illustrated a modification of the present invention that isparticularly adapted to a multiple break circuit interrupter of theso-called rotary type. In this gure of the drawings, the numeral 40designates an insulating support which is adapted'to hold a stationarycontact designated generally by thenumeral 41. 'Ihe stationary contact41 is carried by a suitable insulator engaging member 42 and is disposedbeneath the level of an insulating iluid as is the case in the structurepreviously described. This stationary contact 41 comprises three springpressed contact making members 43 and an arcing tip 44. Mounted totravel in an arcuate path and in cooperating relation with thestationary cont-act .41, there is a movable contact 45.

As shown in Figure 7 of the drawings, the movable contact 45 is disposedupon the end of a rotatable cross arm 46 and cooperates with a secondsimilar movable contact 45 to provide a double break in the circuit whenthe interrupter is in its open position. In this type of circuitinterrupter the rotatable cross arm 46 is generally mounted upon avertically disposed rotatable and insulated support 47 which iscontrolled by a suitable operating mechanism. Secured upon the insulatorengaging member 42 and disposed about the stationary contact 41 is amember 48 which supports acylindrical member 49. The cylindrical member49 which is of insulating material extends outwardly over the stationarycontact 41 and the movable contact 45 to form a confined space orexplosion chamber 50 about the ends of the contacts 41 and 45 when theyare in engagement with each other. At the lower end of the cylindricalmember 49, there is a plug like member 51 having an aperture thereinthrough which the movable con- Clt tact extends into the explosionchamber 50. In this embodiment the explosion chamber is restricted insize by the insertion of a lining member 52.

As shown in Figure 8 of the drawings, the lining member 52 is slottedacross its top to provide a 'clearance for the contact making members 43and the arcing tip 44 of the stationary contact 41. 'This forms twosemi-cylindrical upwardly projecting portions 53 which serve to spacethe lining member 52 axially within the cylindrical member 49. Thelining member 52 is also shown as having one side thereof cut away as at54 to provide for an accumulation of insulating uid directly below thearcing tip 44 of the stationary contact 41. A key-way 55 is providedalong one side of the lining member 52 for securing it against rotationwithin the cylindrical member 49. Two disc like members 56, having aspacing sleeve 5'7 therebetween, are disposed beneath the lining member52 to provide an auxiliary insulating fluid chamber at the lower end ofthe explosion chamber 50. In this embodiment of the invention, insteadof providing a restricted gas discharge outlet at the end of theexplosion chamber 50, the Vmember 48 is formed withv a gas dischargeoutlet 58, through which the gases generated within the explosionchamber 50 may exhaust when an arc is produced within the chamber by aseparation of the contacts. With this arrangement there is provided anauxiliary conductor 59 which extends from the base of the stationarycontact 41 to a point closely adjacent the back of the arcing tip 44. Inorder to restrict the exhaust of gas, from the explosion chamber 50, toa path along the outside of the arcing tip 44, the auxiliary conductor59 is formed, as shown in Figure 9 of the drawings, with a width andshape which, in conjunction with the member 48, will substantially closethe remaining portion of the opening through the member 48. Thisauxiliary conductor 59 is located in spaced relation with the arcing tipsupporting spring so that it will not interfere with the free normalexing thereof. Disposed within the gas discharge outlet 58 and partiallysurrounding the stationary contact 41, there is an insulating bushing60. This bushing 60 serves to insulate the member 48 and insures thatthe arc will travel along the outer surface of the auxiliary conductor59 when its upper root is blown into the gas discharge outlet 58.

Attention is now directed to the manner of securing the cylindricalmember 49 to the supporting member 48 and also closing the lower endthereof. This is important as the cylindrical member 49 is constructedof insulating material, such as iibre or the like, which does not havethe strength of metal. At its upper end the cylindrical member 49projects inside of an annular ange 61 formed upon the member 48 and ithas a metallic ring 62 fitted tightly within its end. This makes itpossible to firmly secure the cylindrical member 49 to the member 48 bya plurality of screws 63 which pass through the flange 61 and arethreaded into the metallic ring 62. These screws 63 may be placed atproperly spaced points about the end of the outwardly extendingcylindrical member 49. At its lower end the cylindrical member 49 isprovided with a reduced annular portion 64 having a metallic ring 65disposed around its outside and a second metallic ring 66 extendingabout its inside. The second ring 66 serves to secure the discs 56 inplace and with the ring 65 it reinforces the reduced annular portion 64of the cylindrical member 49. After the rings 65 and 66 have beenassembled, as above, the plug like member 51 is inserted in the end ofthe cylindrical member 49 and screws 67 are then inserted through thering 65 and threaded into the 'ring 66. The screws 6'7 have projectingends 68 which extend into the plug like member 51 and thus firmly securethe parts together. As an additional element, there is an outercylindrical tube 69 of insulating material which is slipped over thewhole assembly and secured into place by a single screw 70.

The modification illustrated in Figure l0 of the drawings is similar tothat illustrated in Figure 6 of the drawings, except that a member Fl1,which supports the stationary contact 41, is substituted for the vmember48. This member '71 has a restricted gas discharge outlet 72 which isdisposed at one side of and outwardly beyond the end of the explosionchamber, rather than about the stationary contact 41.

The operation of a circuit interrupter constructed in accordance withthis invention should be evident from the above. However, the followingadditional description is thought desirable:

When the contacts 18 and 19 are separated, as when interrupting anelectrical circuit, an arc will be established between the upper end ofthe movable contact 19 and the arcing tip 28 of the stationary contact18. This arc will decompose the surrounding oil or other insulatingfluid and generate a gas within the explosion chamber 15. As the gas isgenerated it will form a continually expanding bubble which will createa pressure within the explosion chamber 15 and as a result the uidlocated within the gas discharge outlet 22 will move outwardly, as apiston of uid, to permit the escape of the gas therethrough.

The movement of this so-called piston of fluid, within the gas dischargeoutlet 22, will be comparatively slow and as a result a high gaspressure will be established within the explosion chamber 15. As soon asthe iluid has been completely displaced from the gas discharge outlet 22the gas will exhaust through this outlet at a high velocity. In otherwords, the piston of uid, within the gas discharge outlet 22, will serveto delay the discharge of gas therethrough sufficiently to permit thebuilding up of a high pressure within the explosion'chamber 15 so thatimmediately upon a clearing of the gas discharge outlet 22 the gas willexhaust at a high velocity. As previously stated, in the preferredarrangement the diameter and length of the insulating tube 27, whichforms the gas discharge outlet 22,*are so proportioned that the iluidlocated therein will be discharged therefrom, to provide a free passagefor the gas, during the first half cycle of arc duration. Under theseconditions the are wm be armed by the exhausting gas from the arcing tip28 to the auxiliary conductor 33 and blown there along until it is nallyextinguished. If the arc persists until the upper end of the movablecontact 19 has been drawn into the auxiliary compartment, formed betweenthe discs 25, the iiuid contained therein will be decomposed and producean additional quantity of arc extinguishing gas.

The operation of the modifications illustrated in Figures 4 and 5 of thedrawings is the same as above described, except that in these modifiedembodiments of the invention the fiarng character of the gas dischargeoutlet 22 will permit a more rapid-discharge of the fluid pistontherefrom.

In the embodiment of the invention illustrated in Figures 6 and 10 ofthe drawings, the gas will be initially formed within the explosionchamber 50 at a point immediately below the arcing tip 44 of thestationary contact 41 and since the gases will follow the line of leastresistance, in their lexhaust from the explosion chamber 50, they willpass around the outside of the arcing tip 44 and thus carry the upperroot of the arc to and along the auxiliary conductor 59 until the arc isextinguished.

While I have, for the sake of clearness and in order to disclose myinvention so that the same can be readily understood, described andillustrated specific devices and arrangements, I desire to have itunderstood that this invention is not limited to the specific meansdisclosed, but may be embodied in other ways that will suggestthemselves to persons skilled in the art. It is believed that thisinvention is new and it is desired to claim it so that all such changesas come within the scope of the appended claims are to be considered aspart of this invention.

Having thusdesc'ribed my invention, what I claim and desire to secure byLetters Patent is- 1. In an explosion chamber for a fluid-break type ofcircuit interrupter, the combination of. a metallic contact supportingmember, a stationary contact upon said supporting member, a tubularmember of insulating material secured at one end to said supportingmember and extending over the stationary contact supported thereby, ametal ring tted tightly Within the other end of said tubular member, aplug like member extending into said metal ring and having a flangedportion' extending outwardly thereover forming with said tubular memberan enclosed explosion chamber, and securing means extending radiallythrough said tubular member and said metal ring and projecting into saidplug like member for securing said members together:

2. In a high tension circuit interrupter of the fluid-break type, thecombination of a tank containing an insulating-huid, an elongatedcylindrical member forming an arc enclosing and gas generating chambersubmerged in said insulating fluid, a ilxed contact disposed within andat one end of said chamber, a moving contact adapted to `extend into theother end of said chamber and engage said ilxed contact, a gas dischargeoutlet in the end of said chamber adjacent said xed contact for thegases generated within said chamber by an arc when the contactsseparate, and a plurality of battles within the other end o! saidchamber cooperating with the insulating tluid therein to provide a'substantially gas tight seal about said moving contact until saidmoving contact has been withdrawn from said chamber.

3. In an explosion chamber for a circuit interrupter of the fluid-breaktype. the combination ot a stationary contact supporting member, astationary contact upon said supporting member and projecting outwardlytherefrom, an outwardly disposed annular iiange carried by said contactsupporting member and extending in spaced relation around saidstationary contact, an open ended tubular member of insulating materialmounted upon said annular ange and extending outwardly beyond saidstationary contact, a movable contact adapted to extend into saidtubular member and cooperate with said stationarycontact, and meanscomprising a plurality of baille like members at the outer end of saidtubular memberv providing a liquid seal about said movable contact whensubmerged in an insulating fluid, whereby gases generated by an arcwithin said tubular member upon a separation of said contacts will becaused to exhaust from the interior of said tubular member through saidannular flange and in a direction opposite to the direction of travel otsaid movable contact.

4. In a circuit interrupter of the fluid-break type, the combination ofa contact supporting member adapted to be submerged in an insulatingfluid, an outwardly disposed annular flange forming an opening throughwhich fluid may circulate, a stationary contact mounted upon saidsupporting member and extending into the opening provided in saidannular flange, an open ended tubular member of insulating materialsecured to said annular flange and extending outwardly from saidstationary contact to form an arc extinguishing chamber, a movablecontact extending into the outer end of said tubular member andadapted-to cooperate with said stationary contact, closure means at theouter end of said tubular member having a central opening through whichsaid movable contact moves and cooperating with said movable contact tosubstantially close the outer end of the arc extinguishing chamberformed by said tubular member, and a baille forming means adiacent saidstationary contact extending into said tubular member and adapted topartially close the opening in said annular ilange to provide a gasdischarge outlet from said arcing chamber at one side of said stationarycontact.

5. In a circuit interrupter of the iluid-break type, the combination ofa contact supporting member adapted to be submerged in an insulatingduid, an outwardly disposed annular ilange forming an opening throughwhich iiuid may circulate, a stationary contact mounted upon saidsupporting member and extending into the opening provided in saidannular flange, an open ended tubular member of insulating materialsecured to said annular iiange and extending 'outwardly from saidstationary contact to form an arc extinguishing chamber, a movablecontact extending through the outer end of said tubular member Vandadapted to cooperate with said stationary contact, closure means at theouter end of said tubular member having a central opening through whichsaid movable contact moves and cooperating with said-movable contact tosubstantially close the outer end of the arc extinguishing chamberformed by said tubular member, and an auxiliary conductor extending intosaid tubular member and partially closing the opening through saidannular flange adapted to conduct an' arc formed within said chamberaway from said stationary contact and into the gas discharged from saidchamber by a decomposition of the insulating iluid therein.-

AUGUST C. SCHWAGER.

